Lining of passageways

ABSTRACT

An underground pipeline or passageway is lined by having a plastics film pre-liner tube applied thereto by inflation, and the tube whilst inflated has an applicator pulled therethrough from which a fluent curable or hardenable composition issues and is applied directly to the inside of the inflated tube to form a layer which cures or hardens to form a lining. Preferably a second tube is applied to the inside of the composition layer to hold it in position whilst it cures or hardens.

This invention relates to the lining of pipelines and passageways,especially the lining of underground pipelines and passageways for therehabilitation, improvement, repair or change of use or coating of suchpipelines or passageways.

There are now established a number of techniques for the lining ofpipelines and passageways, and these techniques are to a greater orlesser extent successful, and the techniques tend to lend themselves toparticular applications. That is to say, some techniques are better forsome circumstances, whilst other techniques are better for othercircumstances.

For example, there are known cement mortar lining techniques whereincement mortar is applied directly to the passageway or pipeline surfaceby spraying, trowelling or by other methods, and such cement mortarlining may be provided with a reinforcement means such as metallic rods,bars or the like. Cement mortar lining techniques are particularlysuitable for large pipelines and passageways where man entry is easy,but as the pipeline or passageway reduces in size until man entry is notpossible, cement mortar lining is not as appropriate as othertechniques, although it is still possible to effect such a lining methodby pulling a spraying device through the pipeline or passageway and byspraying the cement mortar material onto the pipeline or passagewaysurface. Adopting similar methods, it is possible to apply other liningmaterials to passageway surfaces, such as curable synthetic resinousmaterials which like cement mortar harden to provide a rigid lining onthe pipeline or passageway surface. Such synthetic resinous materials,which are of course curable, may or may not be provided withreinforcement as required. Such reinforcement may comprise fibrousmaterials such as glass fibre or scrim or felt materials.

Other techniques which are used for pipeline or passageway liningcomprise the fabrication of a flexible lining tube which embodies anabsorbent layer or layers, and such layer or layers is or areimpregnated thoroughly with a curable synthetic resin at ground level,and then the impregnated bag is fed into the pipeline or passagewaybefore the resin cures, and is held to the surface thereof by fluidpressure until the resin cures forming a rigid lining pipe inside theexisting pipeline or passageway. These techniques are particularlysuitable for the lining of pipelines or passageways which are of thesmaller non-man entry size, although they can be used for man entrypipelines and passageways if required.

Other techniques involve the feeding directly into the pipeline orpassageway of semi-rigid plastic pipes of smaller size than the pipelineor passageway, followed by the filling of the space between the pipelineor passageway and the rigid pipe with a grouting material.

The present invention is concerned with a pipeline or passageway liningmethod Wherein a fluent composition such as cement mortar or a curableresin or the like is sprayed or in suitable circumstances otherwiseapplied to the pipeline or passageway surface so as to form in effect apipe of such fluent material (when it has cured or hardened) lyinginside the existing pipeline or passageway to form a lining for same.

One of the difficulties which arises in connection with the techniquesreferred to above wherein a fluent composition is applied to thepipeline or passageway surface is that the composition will tend toanchor to the pipeline or passageway surface on the one hand, and on theother hand, where the pipeline or passageway surface has crevices orrecesses, the fluent material will tend to flow into such crevices orrecesses and at these locations there will not be an even layer of thecured material because at such locations, the cured material would tendto follow the contour of the crevice or recess. At such location therewill inevitably be a potential weakness point in the lining at best, orcracks or holes in the lining at worst.

There is already known from U.S. Pat. No 4,456,401 a passageway liningmethod wherein a plastic liner tube is applied to the passagewaysurface. The plastic lining tube is provided with a felt which lies tothe inner surface of the liner tube and finally the felt is impregnatedwith curable synthetic resin by a squeegee system. A further plastictube is everted into the passageway by heated water so as to apply auniform pressure to the resin impregnated felt to hold the resin inplace and to initiate the curing of same. The use of a felt and asqueegee makes this process difficult to perform. There is reference tospraying the resin onto the felt tube, but no specific details of suchprocess are given.

Also, there are known from European Patent No 0228998 various methodsfor lining an underground passageway wherein a lining tube assemblycomprising an inner plastic tube, a felt tube impregnated with curableresin and an outer plastic film, is pre-manufactured and then isinserted in the passageway and inflated into the passageway surface, andthe resin is cured so that a hard lining pipe is formed. These methodssuffer from the disadvantage that the assembly has a felt tube which ispre-impregnated with the curable material, and a special impregnationplant is required.

The present invention aims to overcome difficulties with prior methodsand in accordance with the present invention the method of lining apipeline or passageway comprises placing in said pipeline or passagewaya "pre-liner" tube of a construction so that the tube can be inflated,followed by inflation of the tube on to the pipeline or passagewaysurface, followed by the spraying onto the inner surface of the inflatedpre-liner of the fluent composition to form a layer of such compositionon the inner surface of the inflated pre-liner which subsequently curesor is cured to form a rigid pipe of said composition on the pipeline orpassageway surface, the said pre-liner tube being inflated by means of agaseous medium enabling a spraying device to be displaced along theinflated pre-liner tube for the application of said fluent compositionto said surface, characterised in that the "pre-liner" tube is aplastics material film and the composition is sprayed directly onto thefilm surface.

The fluent composition may be supplied with a mixture of drycementitious powder, and water, these ingredients being supplied fromdifferent sources, and mixing in the vicinity of the spraying apparatusor indeed on the inner surface of the inflated pre-liner tube.

Preferably however, the fluent composition will be a cement mortarmaterial or more preferaly a synthetic resinous composition which iscurable and which preferably contains reinforcement fibres in the formof glass fibres.

The fluent composition will preferably be of a viscosity so that it willremain as a coherent and preferably even thickness layer on the inflatedpre-liner inner surface, but if necessary in order to keep thecomposition in place whilst it is cured or cures, after the applicationof the composition there may be everted into the pipeline or passagewaya further holding-tube of suitable plastics material which lies to theinside of the applied composition and holds same in position whilst thecuring takes place.

The invention provides a number of advantages including that thepre-liner prevents the loss of the composition into cracks, fissures andrecesses in the pipeline or passageway surface, as the pre-liner tubewill bridge these imperfections.

Secondly, the pre-liner tube will form a slip plane between thepipeliner or passageway surface and the surface of the rigid pipe formedby the cured composition so that if there is any ground movement givingrise to relative movements of different sections of the pipeline orpassageway surface, such relative movements will either not betransferred to the rigid composition pipe or will not be transmitted tothis pipe to the same extent so that it will not be as liable tofracture in such circumstances as would be a composition pipe created bydirect application of the fluent composition to the pipeline orpassageway surface. The formation of cracks in conventionally appliedcured composition pipes represents a major disadvantage of cement mortarand the like lining techniques and therefore the present inventionrepresents a considerable advance in the art.

An embodiment of the present invention will now be described, by way ofexample, with reference to the accompanying diagrammatic drawings,wherein:

FIG. 1 is a diagrammatic side elevation illustrating the process inoperation:

FIG. 2 is an enlarged sectional elevation illustrating a section of theunderground pipeline shown in FIG. 1 in the region of a pipe joint, forthe purposes of explaining the main advantages of the present invention;and

FIG. 3 is an enlarged view similar to FIG. 2, showing how a holding tubemay be used for holding the curable composition in place, whilst curingis effected.

Referring to the drawings, an underground pipeline or passageway (10) isshown as being lined in accordance with the method according to theembodiment of the invention.

The passageway (10) extends between two manholes (12) and (14) which areused for access in the lining operation.

A pre-liner tube (16) is fed into and along the passageway (10) from onemanhole to the other by conventional means, and the ends of thepre-liner tube are taken to the level (18) of the ground. The ends aresealed by sealing members (20) and (22) so that the interior of thepre-liner tube (16) forms an envelope which can be and is inflated by anair-compressor (24) at ground level which is coupled to the interior ofthe tube (16) through suitable valve and pipe arrangement (26).

Before the tube (16) is thus inflated, a spraying device (28) which canbe moved through the passageway whilst the tube is inflated, ispositioned inside the tube (16), and the device (28) is connected to aground level vehicle (30) from which the supply of the fluentcomposition to form the lining is supplied through a supply tube (32)which sealingly passes through the sealing member (22). The vehicle alsopreferably contains a winching device whereby the spray head on machine(28) can be pulled along the interior of the inflated tube (16) inpassageway (10). A rope (34) is also connected to the device (28), andextends upwardly through the manhole (12) and through the sealing memberas shown. With the arrangement as shown in FIG. 1, the spray device (28)is initially positioned at the left hand end of passageway (10), and itis progressively pulled along the passageway (10) through thepressurised and inflated tube (16), spraying the fluent compositiondirectly onto the interior of the pre-liner tube (12) as shown at (36)as the spray-head proceeds in the direction of arrow (38). The speed ofthe spraying device and the quantity of the fluent composition (36)being sprayed therefrom are calculated so as to provide a layer of thematerial (36) on the inner surface of the pre-liner tube (16) of therequired thickness.

As stated herein, the fluent composition may be any suitable, forexample, a two-part polyurethane or epoxy resin, or a cementitiousmaterial. The fluent composition may be reinforced by means of forexample glass fibres or the like.

Where a resinous material is used it is preferred that the cure timeshould be as short as possible, and in this case it is preferred thatwhere a two-part resin system is used, the resin parts are mixed only inthe spray device (28) so that they will cure or commence cure very soonafter mixing and application to the inner surface of the lining tube(16). The tube (16) is constructed of suitable plastics material such aspolyurethane or pvc.

FIG. 2 shows how the tube (16) functions with advantage. The tube (16)is shown as bridging a pipe-joint gap (40) in FIG. 2, the fluentmaterial (36) forming in fact a rigid pipe on the inner surface of thelining tube (16) also being shown. Assuming that FIG. 2 shows thefinished product, two main advantages are that the fluent material (36)has been prevented from entering the space (40) as it would have donewere the tube (16) omitted, and any such penetration of the space (40)would have resulted in a corresponding groove or recess in the innersurface of the resulting pipe (36) and possibly a weak point in the pipe(36) or even a leakage point therein.

Secondly, by using the film (36) the pipe is prevented from bonding tothe pipe sections (42), (44), defining the passageway so that if in factground movement takes place so that the pipe sections (42) and (44) arerelatively displaced, the tensile forces which normally would have beentransmitted to the pipe (36) were it bonded directly to pipe sections(42) and (44), are avoided and fracture of the pipe (36) is thereforeavoided.

In the arrangement of FIG. 3, a second tube or flexible material similarto tube (16) and forming a holding tube (46) is everted onto the fluentcomposition immediately after it has been sprayed onto the inner surfaceof the tube (16). This technique may be useful when some additionalholding force is required to keep the fluent composition in place untilit cures, but it is preferred that a fluent composition of sufficientviscosity be used so that it will be self-supporting even before curingand until curing takes place. The holding tube may alternativelycomprise a laminate of a fibrous felt having an impermeable outer layer.

Preferably a fluent composition which cures at ambient temperature isutilised, but it is possible to use materials which require theapplication of heat, in which case hot inflation medium would require tobe introduced into the tube (16) so that heat will be applied to thefluent composition immediately after its application to effect orcommence the curing thereof.

Although the thickness of the fluent composition which is applied to thepre-lining tube may be any suitable, it is preferred that it should beof such thickness so that the resulting cured pipe is able to withstandground movement and will also be able to withstand the expectedhydraulic or ground loadings which will be experienced.

The pre-liner tube and the holding tube may be reinforced if requiredwith high strength material such as glass fibre or Kevlar fibre, toenhance the tensile properties thereof.

What is claimed is:
 1. A method of lining a pipeline or passageway, comprising the steps of:a) locating a spraying device inside a pre-liner tube of plastic film; b) inflating said pre-liner tube onto the inner surface of the pipeline or passageway with a gaseous medium; c) while holding the pre-liner tube against the inner surface of the pipeline or passageway with the gaseous medium, moving the spraying device along the pipeline or passageway and spraying a curable fluent composition from the spraying device directly onto the plastic film to form a tubular layer of said composition on the inner surface of the pre-liner tube; and d) curing the tubular layer of said composition to form a rigid pipe on the inner surface of the pre-liner tube; wherein the pre-liner tube is not bonded to the inner surface of the pipeline or passageway so that the pre-liner tube forms a slip plane between the pipeline or passageway and the rigid pipe.
 2. A method according to claim 1, wherein the fluent composition comprises a mixture of dry cementitious powder and water, the method including the further steps of supplying the cementitious powder and water separately to the spraying device and either mixing the dry cementitious powder and water in the spraying device or on the inner surface of the pre-liner tube.
 3. A method according to claim 1, wherein the fluent composition is a cement mortar material or a synthetic resin including reinforcement fibres in the form of glass fibres.
 4. A method according to claim 1, wherein after the spraying of the composition there is everted into the pipeline or passageway a further holding tube to hold the composition in position whilst the curing takes place.
 5. A method according to claim 4, wherein the holding tube comprises a fibrous felt having an impermeable outer layer.
 6. The method according to claim 1, wherein the pre-liner tube is inflated onto the inner surface of an underground passageway. 